Chloride-Promoted High-Rate Ambient Electrooxidation of Methane to Methanol on Patterned Cu–Ti Bimetallic Oxides

The
selective electrochemical methane oxidation reaction
(MOR)
has been challenging due to higher CH4 activation barriers
and lower solubility at ambient conditions. Here, we synthesize a
conductive gas-diffusion layer patterned with alternating squares
of Cu and Ti oxides to achieve highly selective MOR at interfaces
consisting of Cu–Ti bimetallic oxides. We observe high MOR
faradaic efficiencies of ∼28% at ambient conditions and ∼72%
at near-ambient conditions (40 °C) to value-added products such
as CH3OH and HCOOH in a Cl–-mediated
environment. Density function theory calculations suggest that despite
TiO2 exhibiting barrierless thermochemical methane dissociation,
an electrochemical oxidation pathway is likely competitive at high
overpotentials. The unprecedented current densities of ∼10
mA/cm2 for HCOOH and ∼16 mA/cm2 for CH3OH, along with these insights on ambient MOR, will enable
the development of highly efficient electrochemical systems for the
utilization of CH4.